1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device by which a wafer with devices formed in a plurality of regions demarcated by streets formed in a grid pattern in the face-side surface of the wafer is divided along the streets into individual devices, and an adhesive film for die bonding is attached to the back-side surface of each of the devices.
2. Description of the Related Art
For example, in the semiconductor device manufacturing process, devices such as ICs and LSIs are formed in a plurality of regions demarcated by planned dividing lines (streets) formed in a grid pattern in the face-side surface of a roughly circular disk-shaped semiconductor wafer, and the regions provided therein with the devices are divided along the streets, thereby manufacturing the individual semiconductor devices. As a dividing apparatus for dividing the semiconductor wafer, a dicing apparatus is generally used, to cut the semiconductor wafer along the streets by a cutting blade having a thickness of about 20 μm. The semiconductor devices divided in this manner are packaged, to be widely used for electric apparatuses such as mobile phones and personal computers.
To the back-side surface of each of the semiconductor devices divided individually, an adhesive film for die bonding called a die attach film formed from a polyimide resin, an epoxy resin, an acrylic resin or the like and having a thickness of 20 to 40 μm is attached, and the semiconductor devices are attached to a die bonding frame for supporting the semiconductor devices through the adhesive film, by heating. As a method of attaching the adhesive film for die bonding to the back-side surface of each of the semiconductor device, a method is used in which the adhesive film is adhered to the back-side surface of a semiconductor wafer, the semiconductor wafer is adhered to a dicing tape through the adhesive film, and thereafter the semiconductor wafer is cut together with the adhesive film by a cutting blade along streets formed in the face-side surface of the semiconductor wafer, thereby forming the semiconductor devices with the adhesive film attached to the back-side surface thereof (refer to, for example, Japanese Patent Laid-open No. 2000-182995).
According to the method disclosed in Japanese Patent Laid-open No. 2000-182995, however, there is a problem in that at the time of cutting the semiconductor wafer together with the adhesive film by the cutting blade into individual semiconductor devices, chipping may occur at the back-side surfaces of the semiconductor devices or whisker-like burrs may be generated at the adhesive film, causing wire breakage at the time of wire bonding.
In recent years, more reductions in weight and size have been requested as to electric apparatuses such as mobile phones and personal computers, and thinner semiconductor devices have hence been demanded. As a technique for dividing semiconductor devices from each other more thinly, a dividing technique called the dicing-before-grinding method has been put to practical use. The dicing-before-grinding method is a technique in which cut grooves with a predetermined depth (a depth corresponding to a finished thickness of semiconductor devices) are formed along the streets from the face-side surface of the semiconductor wafer, and then the back-side surface of the semiconductor wafer provided with the cut grooves in the face-side surface thereof is ground so as to expose the cut groove on the back side and thereby to divide the semiconductor wafer into individual semiconductor devices. According to this method, the semiconductor devices can be machined to a thickness of 50 μm or below.
However, in the case of dividing a semiconductor wafer into individual semiconductor devices by the dicing-before-grinding method, the cut grooves with a predetermined depth are formed along the streets from the face-side surface of the semiconductor wafer and thereafter the back-side surface of the semiconductor wafer is ground to expose the cut grooves on the back side, so that it is impossible to preliminarily attach an adhesive film for die bonding to the back-side surface of the semiconductor wafer. Therefore, the operation of bonding the semiconductor device to a die bonding frame for supporting the semiconductor device by the dicing-before-grinding method has to be carried out while inserting a bonding agent between the semiconductor device and the die bonding frame, and, hence, the bonding operation cannot be carried out smoothly.
In order to solve such a problem, there has been proposed a method of manufacturing a semiconductor device in which an adhesive film for die bonding is attached to the back-side surface of a wafer divided into individual semiconductor devices by the dicing-before-grinding method and the semiconductor devices are adhered to a dicing tape through the adhesive film, and thereafter, those parts of the adhesive film which are exposed in gaps between the semiconductor devices are irradiated with a laser beam through the gaps from the face side of the semiconductor devices, whereby those parts of the adhesive film which are exposed in the gaps are removed (refer to, for example, Japanese Patent Laid-open No. 2002-118081).
However, when the adhesive film for die bonding which is attached to the back-side surface of the wafer divided into the individual semiconductor devices is irradiated with the laser beam through the gaps between the semiconductor devices to thereby fusion-cut the adhesive film, debris may be scattered to be deposited on the back-side surfaces of the devices, thereby lowering the quality of the semiconductor devices.
In addition, when the adhesive film for die bonding is adhered to the back-side surfaces of the semiconductor devices divided individually by the dicing-before-grinding method and thereafter the protective tape having been adhered to the face-side surface of the wafer is peeled off, the individually divided semiconductor devices are moved. As a result, the gaps composed of the cut grooves formed along the streets come to meander, making it difficult to irradiate the adhesive film with a laser beam through the gaps between the semiconductor devices.